This education program is being submitted with the encouragement and advice of the NCI Training Branch. Advancing nutrition research through expanded education and training programs, especially those related to nutrition and cancer, is a high priority of the Nutritional Science Research Group of the Division of Cancer Prevention at the National Cancer Institute. This application meets the guidelines for the R25T mechanism, including the provision of sustained leadership, dedicated faculty time, a well-defined specialized curriculum, interdisciplinary research environments, and more than one mentor per program participant. This mechanism is particularly appropriate because it is adaptable to the special interdisciplinary, yet focused, needs of this program, which is based on the interface of nutrition and epidemiology. This program is led by Dr. Meir Stampfer, with Dr. Walter Willett as co-Principal Investigator and Dr. Edward Giovannucci as Education Director. The proposed program has a wealth of other resources upon which to draw. The Department of Epidemiology at Harvard School of Public Health has long been a recognized center for didactic training in epidemiologic methods and cancer epidemiology in general. The Department of Nutrition has focused considerable energy in nutritional epidemiology. This educational program also draws on diverse research opportunities within the Dana-Farber/Harvard Cancer Center (DF/HCC), a matrix cancer center representing cancer research across seven Harvard-affiliated institutions. This work has included major developments in the area of diet and cancer such as the creation of three large cohorts comprising over 250,000 men and women with repeated measures of diet followed for as long as 25 years. Participants in this program will also have the opportunity to gain familiarity with other aspects of the broad areas of epidemiology and cancer etiology and prevention that extend beyond the focus of the training grant. Through the proposed training grant, we plan to bring together the various elements already in place, and create new elements to build a coherent and focused interdisciplinary program in nutritional epidemiology of cancer. The proposed training grant in Nutritional Epidemiology of Cancer will provide a unique niche, and it will be complementary, and synergistic, with the other training grants to foster a strong environment for cancer prevention and control, based on sound biology.